The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Integrated circuits (ICs) such as processors typically require power from a plurality of power supplies. Since there are multiple processors (and other ICs) in a given design, there can be multiple power supplies (rails) on a single printed circuit board (PCB). For example, there can be up to 60 power supplies (rails) on a single PCB. Power from the power supplies generally needs to be monitored and controlled. Monitoring and controlling the power supplies typically includes monitoring parameters such as input/output voltages and input/output currents of the power supplies and performing functions such as sequencing. Sequencing a power supply includes determining how to power up, power down, monitor, and reset the power supply. Sequencing can also include fault management.
Generally, the monitoring and controlling is performed using a centralized power-supply controller, monitor, or sequencing IC. The centralized controller may include all or part of a field-programmable gate array (FPGA), a programmable logic device (PLD), an Application Specific Integrated Circuit (ASIC), or a microcontroller (MCU). The centralized controller can monitor and control the power supplies via inter-integrated circuit (I2C) or system management bus (SMBus) sometimes using a power management bus (PMBus) protocol.
The wiring and cost overheads associated with these systems render them unsuitable for use with low-cost, low-power power supplies. For example, when an FPGA, a PLD, or a sequencing/supervisor IC is used to manage individual rails in a power sub-system, such a system is not scalable and is inflexible to design changes. Each sequencing/supervisor IC is generally selected according to a number of power rails in a particular design. Such a system also requires routing of sense nodes across a printed circuit board (PCB), which is subject to noise pick-up and therefore errors.